Fix dotCover parameter syntax

[flaviolazzarini]

As of dotCover 2025.2 JetBrains made significant changes to the parameter syntax of dotCover. Some changes where already made in #4670. Unfortunately not all commands and parameters have been covered. This pull request adds compatibility for the following commands:

• merge
• report

analyse has not been covered, as it's not a supported command anymore.

For a complete list of the commands and their parameters see https://www.jetbrains.com/help/dotcover/dotCover__Console_Runner_Commands.html#help

This fixes #4096

[flaviolazzarini]

@microsoft-github-policy-service agree company="exanicAG"

[devlead]

The direction looks sound and aligns with #4670, but I found one blocking regression and some medium/minor things that should be fixed before merge.

Blocking

DotCoverReport ignores outputFile in new syntax (the default path)

With UseLegacySyntax = false (default), the 3-arg API Report(sourceFile, outputFile, settings) never passes outputFile to the CLI. GenerateArguments only emits --snapshot-source and optional JsonReportOutput / XmlReportOutput from settings.

This breaks the common call pattern:

DotCoverReport(source, new FilePath("./result.xml"), new DotCoverReportSettings());

Previously, this produced /Output=...; now it runs with no output path. The new-syntax tests always set OutputFile = null, so there's no coverage for the default fixture path with a non-null output file.

Suggested fix: When !UseLegacySyntax && outputFile != null, map to the appropriate new flag (e.g., --xml-report-output for default ReportType.XML, --json-report-output for ReportType.JSON). I'd also add a test for that path.

Medium

• Legacy filters are silently dropped on cover: Scope, Filters, AttributeFilters, ProcessFilters, and DisableDefaultFilters are ignored in the new syntax. Scripts using .WithFilter(...) without .WithLegacySyntax() will lose filters with no warning. I'd document this in the release notes and consider a runtime warning when legacy filter collections are populated, but UseLegacySyntax is false.
• HTML / DetailedXML / NDependXML are legacy-only: New report syntax only supports --json-report-output and --xml-report-output. The new DotCoverReport alias example still shows ReportType = HTML, which won't work without legacy syntax.

Minor

• DotCoverReportSettings: XmlReportOutput / XmlReportCoveringTestsScope XML comments say "JSON report" (looks like copy-paste).
• DotCoverReporter.Report(source, settings) XML doc says "Cover" instead of "Report".
• Test regions: typo "Paramter" → "Parameter".
• No DotCoverMerge alias for optional output (tool-level overload exists).
• analyse unchanged, fine with me if that's acknowledged and the command is deprecated in dotCover 2025.2+.

What looks good

• merge / report new syntax (--snapshot-source, --snapshot-output, --temporary-directory, --log-file) looks correct to me.
• Moving UseLegacySyntax to base DotCoverSettings makes sense.
• Lowercase command names match the 2025.2 convention.
• Good legacy vs new test split; build and unit tests pass locally on my machine.

Summary

Area	My take
merge	Good
report	Please fix outputFile regression
cover	OK, I'd document filter migration
Tests	Missing main report output case